Hadjiyannakis, S., Buchholz, A., Chanoine, J. P., Jetha, M. M., Gaboury, L., Hamilton, J., ... & Ball, G. D. (2016). The Edmonton Obesity Staging System for Pediatrics: a proposed clinical staging system for paediatric obesity. Paediatrics & child health, 21(1), 21-26. https://doi.org/10.1093/pch/21.1.21

• Traditionally, clinical recommendations for assessing and managing paediatric obesity have relied on anthropometric measures, such as body mass index (BMI), BMI percentile and/or BMI z-score, to monitor health risks and determine weight management success. However, anthropometric measures do not always accurately and reliably identify children and youth with obesity-related health risks or comorbidities. The authors propose a new clinical staging system (the Edmonton Obesity Staging System for Pediatrics, EOSS-P), adapted from the adult-oriented EOSS. The EOSS-P is used to stratify patients according to severity of obesity-related comorbidities and barriers to weight management into four graded categories (0 to 3) within four main health domains: metabolic, mechanical, mental health and social milieu (the 4Ms). The EOSS-P is based on common clinical assessments that are widely available and routinely completed by clinicians, and has the potential to provide clinical and prognostic information to help evaluate and inform the management of paediatric obesity

Hadjiyannakis, S., Ibrahim, Q., Li, J., Ball, G. D., Buchholz, A., Hamilton, J. K., ... & Morrison, K. M. (2019). Obesity class versus the Edmonton Obesity Staging System for Pediatrics to define health risk in childhood obesity: results from the CANPWR cross-sectional study. The Lancet Child & Adolescent Health, 3(6), 398-407. https://doi.org/10.1016/S2352-4642(19)30056-2

• Background: Disease severity in paediatric obesity is usually defined using the body-mass index (BMI). Although informative at the population level, its usefulness on an individual level has limitations. The use of a clinical staging system—Edmonton Obesity Staging System for Pediatrics (EOSS-P)—in identifying health risk has been proposed. This study aimed to examine the association between BMI class and EOSS-P stage.
• Methods: This cross-sectional study was done in children with obesity aged 5–17 years who enrolled in the Canadian Pediatric Weight Management Registry (CANPWR) between May 31, 2013, and Oct 27, 2017, involving ten multidisciplinary paediatric weight management clinics in Canada. We classified participants into WHO BMI classes (class I as 2–3 SD scores, class II as >3 SD scores, and class III as >4 SD scores above the WHO growth standard median), and applied the EOSS-P staging system (stages 0, 1, and 2/3) based on the clinical assessment of coexisting metabolic, mechanical, mental health, and social milieu issues. Clinical information was extracted from medical records and reported using standardised case report forms. Associations of BMI class with EOSS-P stage were examined in children with complete data.
• Findings: Of the 847 children with complete data, 546 (64%) had severe obesity based on BMI class (ie, class II or III) and 678 (80%) were EOSS-P stage 2/3. Stage 2/3 obesity-related health issues were common; mental health concerns were most common (520 [61%] of 847 children), followed by metabolic (349 [41%] of 847 children), social milieu (179 [21%] of 847 children), and mechanical (86 [10%] of 847 children) health issues. Mental health issues (eg, anxiety and attention-deficit hyperactivity disorder) were equally distributed across BMI classes, metabolic health issues were slightly more common in higher BMI classes, and mechanical (eg, musculoskeletal issues and sleep apnoea) and social milieu (eg, bullying and low household income) issues increased with increasing BMI class. Of children with class I obesity, 206 (76%) of 270 had overall EOSS-P stage 2/3, compared with 195 (85%) of 229 with class III obesity.
• Interpretation: Physical and mental health issues were highly prevalent among children with obesity irrespective of BMI class. Participants with class III obesity carried the greatest health risk across subcategories of the EOSS-P. As BMI class increased, a concomitant increased disease burden in mechanical and social milieu issues was observed, whereas metabolic and mental health risks were high across BMI classes.

Kakon, G. A., Hadjiyannakis, S., Sigal, R. J., Doucette, S., Goldfield, G. S., Kenny, G. P., ... & Alberga, A. S. (2019). Edmonton Obesity Staging System for Pediatrics, quality of life and fitness in adolescents with obesity. Obesity Science & Practice, 5(5), 449-458. https://doi.org/10.1002/osp4.358

• Background: Body mass index (BMI) is often used to diagnose obesity in childhood and adolescence but has limitations as an index of obesity-related morbidity. The Edmonton Obesity Staging System for Pediatrics (EOSS-P) is a clinical staging system that uses weight-related comorbidities to determine health risk in paediatric populations. The purpose of this study was to investigate the associations of EOSS-P and BMI percentile with quality of life (QOL), cardiorespiratory fitness (CRF) and muscular strength in adolescents with obesity.
• Methods: Participants were enrolled at baseline in the Healthy Eating, Aerobic and Resistance Training in Youth trial (BMI = 34.6 ± 4.5 kg m⁻², age = 15.6 ± 1.4 years, N = 299). QOL, CRF (peak oxygen uptake, VO_2peak) and muscular strength were assessed by the Pediatric QOL Inventory (PedsQL), indirect calorimetry during a maximal treadmill test and eight-repetition maximum bench and leg press tests, respectively. Participants were staged from 0 to 3 (absent to severe health risk) according to EOSS-P. Associations were assessed using age-adjusted and sex-adjusted general linear models.
• Results: Quality of life decreased with increasing EOSS-P stages (p < 0.001). QOL was 75.7 ± 11.4 in stage 0/1, 69.1 ± 13.1 in stage 2 and 55.4 ± 13.0 in stage 3. BMI percentile was associated with VO_2peak (β = –0.044 mlO₂ kg⁻¹ min⁻¹ per unit increase in BMI percentile, p < 0.001), bench press (β = 0.832 kg per unit increase in BMI percentile, p = 0.029) and leg press (β = 3.992 kg, p = 0.003). There were no significant differences in treadmill time or VO_2peak between EOSS-P stages (p > 0.05).
• Conclusion: As EOSS-P stages increase, QOL decreases. BMI percentile was negatively associated with CRF and positively associated with muscular strength.